Mr. Powell, the highest-ranking Bush administration official to visit Asia to date, zipped from office to office on the Avenue of Eternal Peace in a head-turning effort to change months of a negative and occasionally hostile tone in US-China relations.

Powell referred to the Chinese as "friends." He went on TV to say the US was "not an enemy" of China. After wide-ranging and seemingly chummy meetings with top Chinese leaders, including President Jiang Zemin, he announced dialogues in four areas, including the sensitive issues of China's high-tech weapons exports and human rights. Talks on human rights have been cancelled since 1999, when NATO bombs hit the Chinese Embassy in Belgrade, Yugoslavia.

In Asia, the single most important relationship - at least the one that most leverages perceptions of stability - is between the US and China, experts say. "What is central to the Asian states is a harmonious US-China relationship," says one high-ranking US military official formerly based in Asia. "In Japan, Korea, in the region, officials don't care about this or that small issue, so long as US-China is healthy. But worries about confrontation - that is destabilizing."

For Asian leaders grown comfortable with a Clinton White House that stressed economic development and downplayed security, the incoming Bush White House often seemed to send conflicting signals. Bush officials say that they want to shift from the "tilt toward China" that they feel was a mistaken Clinton-era policy.

But in Asia, and especially in Beijing, it seemed China was being singled out as a major new threat. The relatively sudden national missile defense (NMD) proposals, record arms-sales approvals to Taiwan, ideas floated from the Pentagon of a "new Pacific strategy" aimed at deterring China, and a new "blue team" of "China threat" hard-liners in key administration positions - all were read here as dramatic change.

In April, a mid-air collision between a US surveillance plane and a Chinese fighter jet sent matters from bad to worse. After the jet crashed, Beijing blamed the accident on the US plane and held the crew for 12 days while seeking a US apology. Relations plummeted - and weren't helped by a series of detentions of US-based ethnic-Chinese scholars (three of whom were released last week, prior to Powell's visit.)

Yet Powell, in Beijing partly to set up a visit by President Bush in October, did little but accentuate the positive. He said the EP-3e plane incident is "pretty much behind us." He praised the "transformation" in Beijing's high-rise landscape, China's booming economy, and the "energy of the Chinese people." He said "the US is prepared to work with China" as it enters the World Trade Organization in November, and congratulated Beijing for winning the right to host the 2008 summer Olympics.

"A constructive relationship is in the interest of China, of Asia, and the world," Powell told reporters. "My presence here today is an example of trying to let the world see that we are not enemies, and we aren't looking for enemies. We are looking for ways to cooperate." The Chinese responded in kind at the one-day blast of effusiveness. "Secretary Powell came at a critical juncture in the relationship," said Foreign Ministry spokesman Sun Yuxi. "We can report good momentum and improvement in developing those relations."

The good feelings are a contrast to Chinese media, that subtly and not-so-subtly paint a negative picture of the US. In a typical "viewer response," aired on Chinese TV the evening Powell was in Beijing, a housewife said that "Americans are aggressive people, Chinese are humble."

Tao Wenzhao, deputy director of the Institute of American Studies at the China Academy of Social Sciences, says US-China relations have been more complex and difficult since the cold war ended, "since you can't tell who is your enemy and who is your friend."

Powell offered that the US is an "Asian and Pacific nation" not only because of its Pacific West Coast, but also because of a large new contingent of Asian-Americans.

Yet, if Powell managed to change the tone and atmosphere of US-China ties, few experts believe that the substance of outstanding disagreements has altered. These include human rights, a maritime agreement that deals with China's claim to airspace above the South China Sea - where the collision took place - trade, and nonproliferation.

On the latter dispute, US officials highlighted China's alleged ongoing missile-technology exports as a prime concern during the trip. Officials told the Washington Post prior to Powell's visit that China was in violation of a November 2000 agreement not to export ballistic-missile components. They said that China had not answered US complaints that sales to Pakistan and Iran continue despite the accord.

The Chinese, for their part, listened to Powell's arguments on developing a missile-defense shield, the secretary said. But Beijing did not alter its opposition to the US plan, which China says will foment an arms race.

On human rights, Powell also said differences remain. A resumed dialogue with the Chinese will begin shortly, however, led by Assistant Secretary of State Lorne Craner, who remained behind.

Yet as Powell left Beijing yesterday for Australia - the last leg of a trip that took him to Japan, Vietnam (for a meeting of Asian foreign ministers in Hanoi), South Korea, and China - US officials felt that Powell's reception and the agreement for new talks at least opened the possibility for constructive work prior to Mr. Bush's visit in October.